Various oxidation catalysts have been proposed for use in a vapor phase catalytic oxidation of olefinically unsaturated hydrocarbons to produce corresponding unsaturated aldehydes with a view of enhancing selectivity for desired unsaturated hydrocarbon without reducing conversion of olefin raw material. The known oxidation catalysts include, for example, cuprous oxide, cupric oxide, bismuth molybdate or bismuth phospho molybdate, cobalt molybdate, antimony oxide, bismuth oxide, vanadium oxide and the like.
U.S. Pat. No. 3,454,630 describes a process for converting propylene and isobutylene to the corresponding unsaturated aldehydes and carboxylic acids in the presence of a catalyst of the elements of Ni, Co, Fe, Bi, P, Mo, O. In U.S. Pat. No. 3,454,630 propylene is oxidized to acrolein in a maximum single pass yield of 71 percent. In Canadian Patent 781,513 the maximum single pass yield of acrolein from propylene is 75.5 percent in the presence of a Ni, Co, Fe, As, Mo, O catalyst.
U.S. Pat. No. 3,778,386 describes a vapor phase oxidation process in which propylene can be converted to acrolein in a single pass yield up to 88 percent. ##EQU1## The U.S. Pat. No. 3,778,386 catalyst contained the following elements on a suitable carrier or binder: EQU Ni.sub.a Co.sub.b Fe.sub.c Bi.sub.d L.sub.e M.sub.h Mo.sub.f O.sub.g
wherein Ni, Co, Fe, Bi, Mo and O are the elements nickel, cobalt, iron, bismuth, molybdenum and oxygen, respectively; L is phosphorous, arsenic or boron, including mixtures; and M is potassium, rubidium or cesium, including mixtures; and wherein a and b are 0 to 15, while a plus b is 2 to 15, c is 0.5 to 7, d is 0.1 to 4, e is 0 to 4, f is 12, g is 35 to 85 and h is 0.01 to 0.5.
U.S. Pat. No. 4,001,317 describes a process for the preparation of unsaturated aldehydes and acids from propylene or isobutylene by the vapor phase oxidation of propylene or isobutylene with molecular oxygen at a temperature of about 200.degree. to 600.degree. C. in the presence of a catalyst, the improvement comprising using as the catalyst a catalyst of the formula: EQU Ce.sub.a A.sub.b D.sub.c E.sub.d Fe.sub.f Bi.sub.g Mo.sub.12 O.sub.x
wherein A is an alkali metal, Tl or a mixture thereof; D is Ni, Co, Mg, Zn, Cd, Ca, Sr or mixture thereof; E is P, As, B, S, Al or mixture thereof; and wherein a is greater than 0 but less than 5; b and d are 0-4; c, f and g are 0.1-12; and x is the number of oxygens required to satisfy the valence requirements of the other elements present.
As noted in the above described prior art processes, when propylene or isobutylene is catalytically oxidized into acrolein or methacrolein in the vapor phase, substantial amounts of byproducts are formed such as carbon monoxide, carbon dioxide, saturated aldehydes (e.g., formaldehyde and acetaldehyde) and acids (e.g., acetic acid and acrylic acid). Furthermore, catalysts which promote acceptable conversion yield and selectively in the vapor phase oxidation of propylene or isobutylene to acrolein or methacrolein often exhibit a short catalyst life.
Accordingly, it is a main object of this invention to provide an improved process for high single pass conversion of olefins into the corresponding unsaturated aldehyde derivatives.
It is another object of this invention to provide an improved oxidation catalyst for conversion of acrolein or isobutylene to acrolein or methacrolein with a single pass olefin conversion of at least 95 percent and an unsaturated aldehyde product efficiency of at least 70 percent.
It is a further object of this invention to provide a process for preparing a Mo--Co--Fe--Ni--Bi--K--P--O oxidation catalyst which exhibits extended catalytic activity in vapor phase olefin oxidation processes.
Other objects and advantages shall become apparent from the accompanying description and examples.